What are some alternatives?
When comparing Impro-Visor and Sibelius, you can also consider the following products
MuseScore - 24 Sep 2012 . Design a homepage that captures attention and serves as a good starting point for navigating the website.
Guitar Pro 7 - Create, play and share your tabs
Band-in-a-Box - Band-in-a-Box is so easy to use!
Finale - Finale, the world standard for music notation software, lets you compose, arrange, notate, and print engraver-quality sheet music.
TuxGuitar - A Multitrack tablature editor and player.
OpenMPT - OpenMPT is a popular tracker software for Windows.